Electron discharge device



1959 s. RISHELL ELECTRON DISCHARGE DEVICE Filed Dec. 5, 1957 INVENTOR GEORGE L. R/SHELL ATTORNEY United States Patent ELECTRON DISCHARGE DEVICE George L. Rishell, Emporium, Pa., assign'or, by mesne assignments, to Sylvania Electric Products Inc., Wilmington, Del., a corporation of Delaware Application December 5, 1957, Serial No. 700,836

1 Claim. (Cl. 313-238) This invention relates to electrical devices such as electron discharge tubes and more particularly to tubes of the high voltage rectifier type.

High voltage rectifiers such as the 1B3GT, which are employed in the high voltage circuit of a television receiver, generally employ a bell-shaped anode and a helical filamentary cathode positioned Within the anode. Due to the high voltage existing between the anode and cathode during tube operation, large electrostatic forces are exerted upon the filament which tend to flex and distort the helix. This distortion reduces the useful life of the tube due to rupture of the cathode material, broken filament wire and broken weld joints.

Accordingly, it is an object of the invention to reduce the aforementioned disadvantages, and to increase the useful life of electron tubes.

A further object is to reduce cathode distortion in an electron tube and to provide improved cathode emission characteristics.

A further object of the invention is to simplify mounting procedures utilized in the construction of electron tubes.

The foregoing objects are achieved in one aspect of the invention by the provision of an electron tube having a cylindrical anode with an indirectly heated rigid tubular cathode mounted therein. The cathode employs spaced tabs which are connected to a common conductive support rod. The heater element is disposed within the cathode and is provided with lead wires, one of which is attached to the cathode support rod. The other heater lead is coupled to a separate electrical connector.

A cathode structure of the type described herein has sufiicient strength and rigidity to withstand the electrostatic forces exerted upon it. In addition, due to the large electron emissive area directed toward the anode, improved emission characteristics are achieved. The cathode mounting positions and electrical connections are simplified due to the application of a cathode support rod which also serves as the electrical connection for the cathode and for one of the heater legs.

For a better understanding of the invention, reference is made to the following description taken in conjunction with the accompanying drawings in which:

Fig. 1 is a partially sectioned plan view of a typical diode rectifier type electron tube; and

Fig. 2 is a plan view of a cathode assembly capable of being utilized in the tube illustrated in Fig. 1.

Referring to the drawings, a high voltage rectifier 11 is illustrated with an envelope 13 and a base 15 provided with electrical lead pins 17, which are formed to connect the internal tube electrodes with their appropriate 2,909,699 Patented Oct. 20, 1959 electrical circuits. Hermetically mounted within envelope 13 is a cathode 19 and an anode 21 having a top cap connector 23 sealed into the dome of the envelope. The anode is formed with a bell-shaped body portion 25, a base 27 and an opening 29 disposed along the 1ongitudinal axis thereof opposite to the base.

The indirectly heated cathode 19 has a tubular metallic sleeve 31 coated over its central area with an electron emissive material 33. Two tabs 35 extend in opposite directions from the sleeve along the longitudinal axis thereof to provide rigid support for the cathode as will be hereafter described.

A heater 37 is disposed within cylinder 31 to provide the temperature needed to cause electron emission from material 33. That portion of the heater wire which lies within the cathode is coated with insulating material 39 while the ends of the heater leads 41 are free from coating to facilitate welding to provide electrical connections.

Cathode 19 is mounted within anode 21 by means of weld connections between tabs 35 and support member 43, which is formed with cross arms 45 and 47. Member 43 may be bent at its upper end to form arm 45 while arm 47 may comprise a strap welded to the vertical rod portion of rod 43. One of the heater legs 41, in addition to the cathode sleeve 31 through tabs 35, is electrically connected to lug 44 by support member 43. The other heater leg 41 is electrically coupled to heater lead connector 49 and lug 51. Mounted below anode 21 is an electron shield 53. This shield is held in position by lugs 44 and 55.

An electron tube constructed in accordance with this invention has improved structural strength and improved emission characteristics, and it is formed to facilitate increased production by virtue of a simplified lay-out of parts.

Although one embodiment of the invention has been shown and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claim.

What is claimed is:

An electron discharge device comprising a cylindrical anode, a rigid tubular indirectly heated cathode disposed within said anode along the longitudinal axis thereof having first and second tabs extending longitudinally outward from opposite ends of said cathode, a heater disposed within said cathode having two electrical leads extending from one end thereof disposed adjacent said first tab, a conductive support member formed with lower and upper cross arms straddling said cathode and attached to said first and second tabs respectively, and a heater lead connector disposed adjacent and spaced from said lower cross arm, one of said heater leads being coupled to said lower cross arm, the other of said heater leads being coupled to said heater lead connector.

References Cited in the file of this patent UNITED STATES PATENTS Re. 19,870 Lederer Feb. 25, 1936 1,868,604 Horn July 26, 1932 2,582,684 Drieschman Jan. 15, 1952 2,656,479 Brown Oct. 20, 1953 2,871,391 Schade Jan. 27, 1959 

